dns_requester structure can be allocated at run time when servers get
associated to DNS resolution (this happens when SRV records are used in
conjunction with service discovery).
Well, this memory allocation is safer if managed in an HAProxy pool,
furthermore with upcoming HTTP action which can perform DNS resolution
at runtime.
This patch moves the memory management of the dns_requester structure
into its own pool.
task_delete() was never used without calling task_free() just after, and
task_free() was only used on error pathes to destroy a just-created task,
so merge them into task_destroy(), that will remove the task from the
wait queue, and make sure the task is either destroyed immediately if it's
not in the run queue, or destroyed when it's supposed to run.
In dns_read_name() when dns name is used with compression and start position of
name is greater than 255 name read is incorrect and causes invalid dns error.
eg: 0xc11b c specifies name compression being used. 11b represent the start
position of name but currently we are using only 1b for start position.
This should be backported as far as 1.7.
A regression was introduced with efbbdf72 BUG: dns: Prevent out-of-bounds
read in dns_validate_dns_response() as it prevented from taking into account
the last byte of the payload. this patch aims at fixing it.
this must be backported in 1.8.
We need to make sure that the record length is not making us read
past the end of the data we received.
Before this patch we could for example read the 16 bytes
corresponding to an AAAA record from the non-initialized part of
the buffer, possibly accessing anything that was left on the stack,
or even past the end of the 8193-byte buffer, depending on the
value of accepted_payload_size.
To be backported to 1.8, probably also 1.7.
Some callers of dns_read_name() do not make sure that we can read
the first byte, holding the length of the next label, without going
past our buffer, so we need to make sure of that.
In addition, if the label is a compressed one we need to make sure
that we can read the following byte to compute the target offset.
To be backported to 1.8, probably also 1.7.
When a compressed pointer is encountered, dns_read_name() will call
itself with the pointed-to offset in the packet.
With a specially crafted packet, it was possible to trigger an
infinite-loop recursion by making the pointer points to itself.
While it would be possible to handle that particular case differently
by making sure that the target is different from the current offset,
it would still be possible to craft a packet with a very long chain
of valid pointers, always pointing backwards. To prevent a stack
exhaustion in that case, this patch restricts the number of recursive
calls to 100, which should be more than enough.
To be backported to 1.8, probably also 1.7.
Instead of exporting a number of pools and having to manually delete
them in deinit() or to have dedicated destructors to remove them, let's
simply kill all pools on deinit().
For this a new function pool_destroy_all() was introduced. As its name
implies, it destroys and frees all pools (provided they don't have any
user anymore of course).
This allowed to remove 4 implicit destructors, 2 explicit ones, and 11
individual calls to pool_destroy(). In addition it properly removes
the mux_pt_ctx pool which was not cleared on exit (no backport needed
here since it's 1.9 only). The sig_handler pool doesn't need to be
exported anymore and became static now.
This commit replaces the explicit pool creation that are made in
constructors with a pool registration. Not only this simplifies the
pools declaration (it can be done on a single line after the head is
declared), but it also removes references to pools from within
constructors. The only remaining create_pool() calls are those
performed in init functions after the config is parsed, so there
is no more user of potentially uninitialized pool now.
It has been the opportunity to remove no less than 12 constructors
and 6 init functions.
Most calls to hap_register_post_check(), hap_register_post_deinit(),
hap_register_per_thread_init(), hap_register_per_thread_deinit() can
be done using initcalls and will not require a constructor anymore.
Let's create a set of simplified macros for this, called respectively
REGISTER_POST_CHECK, REGISTER_POST_DEINIT, REGISTER_PER_THREAD_INIT,
and REGISTER_PER_THREAD_DEINIT.
Some files were not modified because they wouldn't benefit from this
or because they conditionally register (e.g. the pollers).
This switches explicit calls to various trivial registration methods for
keywords, muxes or protocols from constructors to INITCALL1 at stage
STG_REGISTER. All these calls have in common to consume a single pointer
and return void. Doing this removes 26 constructors. The following calls
were addressed :
- acl_register_keywords
- bind_register_keywords
- cfg_register_keywords
- cli_register_kw
- flt_register_keywords
- http_req_keywords_register
- http_res_keywords_register
- protocol_register
- register_mux_proto
- sample_register_convs
- sample_register_fetches
- srv_register_keywords
- tcp_req_conn_keywords_register
- tcp_req_cont_keywords_register
- tcp_req_sess_keywords_register
- tcp_res_cont_keywords_register
- flt_register_keywords
Remaining calls to si_cant_put() were all for lack of room and were
turned to si_rx_room_blk(). A few places where SI_FL_RXBLK_ROOM was
cleared by hand were converted to si_rx_room_rdy().
The now unused si_cant_put() function was removed.
This flag is not enough to describe all blocking situations, as can be
seen in each case we remove it. The muxes has taught us that using multiple
blocking flags in parallel will be much easier, so let's start to do this
now. This patch only renames this flags in order to make next changes more
readable.
Like for the other checks, the type is being tested just before calling
objt_{server,dns_srvrq}() so let's use the unguarded version instead to
silence the warning.
On the Mailing list, Marcos Moreno reported that haproxy configuration
validation (through "haproxy -c cfgfile") does not detect when a
resolvers section does not exist for a server.
That said, this checking is done after HAProxy has started up.
The problem is that this can create production issue, since init
script can't detect the problem before starting / reloading HAProxy.
To fix this issue, this patch registers the function which validates DNS
configuration validity and run it right after configuration parsing is
finished (through cfg_register_postparser()).
Thanks to it, now "haproxy -c cfgfile" will fail when a server
points to a non-existing resolvers section (or any other validation made
by the function above).
Backport status: 1.8
By convenience or laziness we used to store dns_build_query()'s return code
into trash.data. The result checks applied there compare trash.data to -1
while it's now unsigned since commit 843b7cb ("MEDIUM: chunks: make the
chunk struct's fields match the buffer struct"). Let's clean this up
and test the result itself without storing it first.
No backport is needed.
Chunks are only a subset of a buffer (a non-wrapping version with no head
offset). Despite this we still carry a lot of duplicated code between
buffers and chunks. Replacing chunks with buffers would significantly
reduce the maintenance efforts. This first patch renames the chunk's
fields to match the name and types used by struct buffers, with the goal
of isolating the code changes from the declaration changes.
Most of the changes were made with spatch using this coccinelle script :
@rule_d1@
typedef chunk;
struct chunk chunk;
@@
- chunk.str
+ chunk.area
@rule_d2@
typedef chunk;
struct chunk chunk;
@@
- chunk.len
+ chunk.data
@rule_i1@
typedef chunk;
struct chunk *chunk;
@@
- chunk->str
+ chunk->area
@rule_i2@
typedef chunk;
struct chunk *chunk;
@@
- chunk->len
+ chunk->data
Some minor updates to 3 http functions had to be performed to take size_t
ints instead of ints in order to match the unsigned length here.
By default, HAProxy's DNS resolution at runtime ensure that there is no
IP address duplication in a backend (for servers being resolved by the
same hostname).
There are a few cases where people want, on purpose, to disable this
feature.
This patch introduces a couple of new server side options for this purpose:
"resolve-opts allow-dup-ip" or "resolve-opts prevent-dup-ip".
dns_get_ip_from_response() is used to compare the caller current IP to
the IP available in the records returned by the DNS server.
A scoring system is in place to get the best IP address available.
That said, in the current implementation, there are a couple of issues:
1. a comment does not match what the code does
2. the code does not match what the commet says (score value is not
incremented with '2')
This patch fixes both issues.
Backport status: 1.8
The comment was about "prefered network ip version" while it's actually
"prefered ip version" in the code.
Fixed
Backport status: 1.7 and 1.8
Be careful, this patch may not apply on 1.7, since the score was '4'
for this item at that time.
In preparation for thread-specific runqueues, change the task API so that
the callback takes 3 arguments, the task itself, the context, and the state,
those were retrieved from the task before. This will allow these elements to
change atomically in the scheduler while the application uses the copied
value, and even to have NULL tasks later.
When checks fail, the code tries to run a dns resolution, in case the IP
changed.
The old way of doing that was to check, in case the last dns resolution
hadn't expired yet, if there were an applicable IP, which should be useless,
because it has already be done when the resolution was first done, or to
run a new resolution.
Both are a locking nightmare, and lead to deadlocks, so instead, just wake the
resolvers task, that should do the trick.
This should be backported to 1.8.
In order to use arbitrary data in the CLI (multiple lines or group of words
that must be considered as a whole, for example), it is now possible to add a
payload to the commands. To do so, the first line needs to end with a special
pattern: <<\n. Everything that follows will be left untouched by the CLI parser
and will be passed to the commands parsers.
Per-command support will need to be added to take advantage of this
feature.
Signed-off-by: Aurélien Nephtali <aurelien.nephtali@corp.ovh.com>
issue was identified by cppcheck
[src/dns.c:2037] -> [src/dns.c:2041]: (warning) Variable 'appctx->st2' is reassigned a value before the old one has been used. 'break;' missing?
Automatic downgrade of DNS accepted payload size may have undesired side
effect, which could make a backend with all servers DOWN.
After talking with Lukas on the ML, I realized this "feature" introduces
more issues that it fixes problem.
The "best" way to handle properly big responses will be to implement DNS
over TCP.
To be backported to 1.8.
fd_insert() is currently called just after setting the owner and iocb,
but proceeding like this prevents the operation from being atomic and
requires a lock to protect the maxfd computation in another thread from
meeting an incompletely initialized FD and computing a wrong maxfd.
Fortunately for now all fdtab[].owner are set before calling fd_insert(),
and the first lock in fd_insert() enforces a memory barrier so the code
is safe.
This patch moves the initialization of the owner and iocb to fd_insert()
so that the function will be able to properly arrange its operations and
remain safe even when modified to become lockless. There's no other change
beyond the internal API.
A SRV record weight can range from 0 to 65535, while haproxy weight goes
from 0 to 256, so we have to divide it by 256 before handing it to haproxy.
Also, a SRV record with a weight of 0 doesn't mean the server shouldn't be
used, so use a minimum weight of 1.
This should probably be backported to 1.8.
During the migration to the second version of the pools, the new
functions and pool pointers were all called "pool_something2()" and
"pool2_something". Now there's no more pool v1 code and it's a real
pain to still have to deal with this. Let's clean this up now by
removing the "2" everywhere, and by renaming the pool heads
"pool_head_something".
Rename the global variable "proxy" to "proxies_list".
There's been multiple proxies in haproxy for quite some time, and "proxy"
is a potential source of bugs, a number of functions have a "proxy" argument,
and some code used "proxy" when it really meant "px" or "curproxy". It worked
by pure luck, because it usually happened while parsing the config, and thus
"proxy" pointed to the currently parsed proxy, but we should probably not
rely on this.
[wt: some of these are definitely fixes that are worth backporting]
snr_check_ip_callback() may be called with the server lock, so don't attempt
to lock it again, instead, make sure the callers always have the lock before
calling it.
srv_set_fqdn() may be called with the DNS lock already held, but tries to
lock it anyway. So, add a new parameter to let it know if it was already
locked or not;
2 global locks have been added to protect, respectively, the run queue and the
wait queue. And a process mask has been added on each task. Like for FDs, this
mask is used to know which threads are allowed to process a task.
For many tasks, all threads are granted. And this must be your first intension
when you create a new task, else you have a good reason to make a task sticky on
some threads. This is then the responsibility to the process callback to lock
what have to be locked in the task context.
Nevertheless, all tasks linked to a session must be sticky on the thread
creating the session. It is important that I/O handlers processing session FDs
and these tasks run on the same thread to avoid conflicts.
This is a huge patch with many changes, all about the DNS. Initially, the idea
was to update the DNS part to ease the threads support integration. But quickly,
I started to refactor some parts. And after several iterations, it was
impossible for me to commit the different parts atomically. So, instead of
adding tens of patches, often reworking the same parts, it was easier to merge
all my changes in a uniq patch. Here are all changes made on the DNS.
First, the DNS initialization has been refactored. The DNS configuration parsing
remains untouched, in cfgparse.c. But all checks have been moved in a post-check
callback. In the function dns_finalize_config, for each resolvers, the
nameservers configuration is tested and the task used to manage DNS resolutions
is created. The links between the backend's servers and the resolvers are also
created at this step. Here no connection are kept alive. So there is no needs
anymore to reopen them after HAProxy fork. Connections used to send DNS queries
will be opened on demand.
Then, the way DNS requesters are linked to a DNS resolution has been
reworked. The resolution used by a requester is now referenced into the
dns_requester structure and the resolution pointers in server and dns_srvrq
structures have been removed. wait and curr list of requesters, for a DNS
resolution, have been replaced by a uniq list. And Finally, the way a requester
is removed from a DNS resolution has been simplified. Now everything is done in
dns_unlink_resolution.
srv_set_fqdn function has been simplified. Now, there is only 1 way to set the
server's FQDN, independently it is done by the CLI or when a SRV record is
resolved.
The static DNS resolutions pool has been replaced by a dynamoc pool. The part
has been modified by Baptiste Assmann.
The way the DNS resolutions are triggered by the task or by a health-check has
been totally refactored. Now, all timeouts are respected. Especially
hold.valid. The default frequency to wake up a resolvers is now configurable
using "timeout resolve" parameter.
Now, as documented, as long as invalid repsonses are received, we really wait
all name servers responses before retrying.
As far as possible, resources allocated during DNS configuration parsing are
releases when HAProxy is shutdown.
Beside all these changes, the code has been cleaned to ease code review and the
doc has been updated.
The cli command to show resolvers stats is in conflict with the command to show
proxies and servers stats. When you use the command "show stat resolvers [id]",
instead of printing stats about resolvers, you get the stats about all proxies
and servers.
Now, to avoid conflict, to print resolvers stats, you must use the following
command:
show resolvers [id]
This patch must be backported in 1.7.
For HTTP/2 we'll need some buffer-only equivalent functions to some of
the ones applying to channels and still squatting the bi_* / bo_*
namespace. Since these names have kept being misleading for quite some
time now and are really getting annoying, it's time to rename them. This
commit will use "ci/co" as the prefix (for "channel in", "channel out")
instead of "bi/bo". The following ones were renamed :
bi_getblk_nc, bi_getline_nc, bi_putblk, bi_putchr,
bo_getblk, bo_getblk_nc, bo_getline, bo_getline_nc, bo_inject,
bi_putchk, bi_putstr, bo_getchr, bo_skip, bi_swpbuf
This patch adds the ability to read from a wrapping memory area (ie:
buffers). The new functions are called "readv_<type>". The original
ones were renamed to start with "read_" to make the difference more
obvious between the read method and the returned type.
It's worth noting that the memory barrier in readv_bytes() is critical,
as otherwise gcc decides that it doesn't need the resulting data, but
even worse, removes the length checks in readv_u64() and happily
performs an out-of-bounds unaligned read using read_u64()! Such
"optimizations" are a bit borderline, especially when they impact
security like this...
Since the DNS layer split and the use of obj_type structure, we did not
updated propoerly the code used to compute the interval between 2
resolutions.
A nasty loop was then created when:
- resolver's hold.valid is shorter than servers' check.inter
- a valid response is available in the DNS cache
A task was woken up for a server's resolution. The servers pick up the IP
in the cache and returns without updating the 'last update' timestamp of
the resolution (which is normal...). Then the task is woken up again for
the same server.
The fix simply computes now properly the interval between 2 resolutions
and the cache is used properly while a new resolution is triggered if
the data is not fresh enough.
a reader pointer comparison to the end of the buffer was performed twice
while once is obviously enough.
backport status: this patch can be backported into HAProxy 1.6 (with some
modification. Please contact me)
For troubleshooting purpose, it may be important to know when a server
got its fqdn updated by a SRV record.
This patch makes HAProxy to report such events through stderr and logs.
RFC 6891 states that if a DNS client announces "big" payload size and
doesn't receive a response (because some equipments on the path may
block/drop UDP fragmented packets), then it should try asking for
smaller responses.
Following up DNS extension introduction, this patch aims at making the
computation of the maximum number of records in DNS response dynamic.
This computation is based on the announced payload size accepted by
HAProxy.
This patch fixes a bug where some servers managed by SRV record query
types never ever recover from a "no resolution" status.
The problem is due to a wrong function called when breaking the
server/resolution (A/AAAA) relationship: this is performed when a server's SRV
record disappear from the SRV response.
Edns extensions may be used to negotiate some settings between a DNS
client and a server.
For now we only use it to announce the maximum response payload size accpeted
by HAProxy.
This size can be set through a configuration parameter in the resolvers
section. If not set, it defaults to 512 bytes.
Current code implementation prevents multiple backends from relying on
the same SRV resolution. Actually, only the first backend which triggers
the resolution gets updated.
This patch makes HAProxy to process the whole list of the 'curr'
requesters to apply the changes everywhere (hence, the cache also applies
to SRV records...)
This function is particularly useful when debugging DNS resolution at
run time in HAProxy.
SRV records must be read differently, hence we have to update this
function.
DNS SRV records uses "dns name compression" to store the target name.
"dns compression" principle is simple. Let's take the name below:
3336633266663038.red.default.svc.cluster.local.
It can be stored "as is" in the response or it can be compressed like
this:
3336633266663038<POINTER>
and <POINTER> would point to the string
'.red.default.svc.cluster.local.' availble in the question section for
example.
This mechanism allows storing much more data in a single DNS response.
This means the flag "record->data_len" which stores the size of the
record (hence the whole string, uncompressed) can't be used to move the
pointer forward when reading responses. We must use the "offset" integer
which means the real number of bytes occupied by the target name.
If we don't do that, we can properly read the first SRV record, then we
loose alignment and we start reading unrelated data (still in the
response) leading to a false negative error treated as an "invalid"
response...
DNS response for SRV queries look like this:
- query dname looks like '_http._tcp.red.default.svc.cluster.local'
- answer record dname looks like
'3336633266663038.red.default.svc.cluster.local.'
Of course, it never matches... and it triggers many false positive in
the current code (which is suitable for A/AAAA/CNAME).
This patch simply ignores this dname matching in the case of SRV query
type.
First implementation of the DNS parser used to consider TRUNCATED
responses as errors and triggered a failover to an other query type
(usually A to AAAA or vice-versa).
When we query for SRV records, a TRUNCATED response still contains valid
records we can exploit, so we shouldn't trigger a failover in such case.
Note that we had to move the maching against the flag later in the
response parsing (actually, until we can read the query type....)
Make it so for each server, instead of specifying a hostname, one can use
a SRV label.
When doing so, haproxy will first resolve the SRV label, then use the
resulting hostnames, as well as port and weight (priority is ignored right
now), to each server using the SRV label.
It is resolved periodically, and any server disappearing from the SRV records
will be removed, and any server appearing will be added, assuming there're
free servers in haproxy.
As DNS servers may not return all IPs in one answer, we want to cache the
previous entries. Those entries are removed when considered obsolete, which
happens when the IP hasn't been returned by the DNS server for a time
defined in the "hold obsolete" parameter of the resolver section. The default
is 30s.
The commit 201c07f68 ("MAJOR/REORG: dns: DNS resolution task and
requester queues") introduces a warning during compilation:
src/dns.c: In function ‘dns_resolve_recv’:
src/dns.c:487:6: warning: ‘need_resend’ may be used uninitialized in this function [-Wmaybe-uninitialized]
if (need_resend) {
^
This patch initialize the variable and remove the comment about it.
This patch is a major upgrade of the internal run-time DNS resolver in
HAProxy and it brings the following 2 main changes:
1. DNS resolution task
Up to now, DNS resolution was triggered by the health check task.
From now, DNS resolution task is autonomous. It is started by HAProxy
right after the scheduler is available and it is woken either when a
network IO occurs for one of its nameserver or when a timeout is
matched.
From now, this means we can enable DNS resolution for a server without
enabling health checking.
2. Introduction of a dns_requester structure
Up to now, DNS resolution was purposely made for resolving server
hostnames.
The idea, is to ensure that any HAProxy internal object should be able
to trigger a DNS resolution. For this purpose, 2 things has to be done:
- clean up the DNS code from the server structure (this was already
quite clean actually) and clean up the server's callbacks from
manipulating too much DNS resolution
- create an agnostic structure which allows linking a DNS resolution
and a requester of any type (using obj_type enum)
3. Manage requesters through queues
Up to now, there was an uniq relationship between a resolution and it's
owner (aka the requester now). It's a shame, because in some cases,
multiple objects may share the same hostname and may benefit from a
resolution being performed by a third party.
This patch introduces the notion of queues, which are basically lists of
either currently running resolution or waiting ones.
The resolutions are now available as a pool, which belongs to the resolvers.
The pool has has a default size of 64 resolutions per resolvers and is
allocated at configuration parsing.
This patch introduces a bit of roundrobin in the records stored in our
local cache.
Purpose is to allow some kind of distribution of the IPs found in a
response.
Note that distribution properly applies only when the IP used by many
requesters disappear and is replaced by an other one.
ancount is the number of answers available in a DNS response.
Before this patch, HAProxy used to store the ancount found in the buffer
(sent by the DNS server).
Unfortunately, this is now inaccurate and does not correspond to the
number of records effectively stored in our local version of the
response. In Example, the CNAMEs are not stored.
This patch updates ancount field in to make it match what is effectively
stored in our version.
Introduction of a DNS response LRU cache in HAProxy.
When a positive response is received from a DNS server, HAProxy stores
it in the struct resolution and then also populates a LRU cache with the
response.
For now, the key in the cache is a XXHASH64 of the hostname in the
domain name format concatened to the query type in string format.
Prior this patch, the DNS responses were stored in a pre-allocated
memory area (allocated at HAProxy's startup).
The problem is that this memory is erased for each new DNS responses
received and processed.
This patch removes the global memory allocation (which was not thread
safe by the way) and introduces a storage of the dns response in the
struct
resolution.
The memory in the struct resolution is also reserved at start up and is
thread safe, since each resolution structure will have its own memory
area.
For now, we simply store the response and use it atomically per
response per server.
In the process of breaking links between dns_* functions and other
structures (mainly server and a bit of resolution), the function
dns_get_ip_from_response needs to be reworked: it now can call
"callback" functions based on resolution's owner type to allow modifying
the way the response is processed.
For now, main purpose of the callback function is to check that an IP
address is not already affected to an element of the same type.
For now, only server type has a callback.
This patch introduces a some re-organisation around the DNS code in
HAProxy.
1. make the dns_* functions less dependent on 'struct server' and 'struct resolution'.
With this in mind, the following changes were performed:
- 'struct dns_options' has been removed from 'struct resolution' (well,
we might need it back at some point later, we'll see)
==> we'll use the 'struct dns_options' from the owner of the resolution
- dns_get_ip_from_response(): takes a 'struct dns_options' instead of
'struct resolution'
==> so the caller can pass its own dns options to get the most
appropriate IP from the response
- dns_process_resolve(): struct dns_option is deduced from new
resolution->requester_type parameter
2. add hostname_dn and hostname_dn_len into struct server
In order to avoid recomputing a server's hostname into its domain name
format (and use a trash buffer to store the result), it is safer to
compute it once at configuration parsing and to store it into the struct
server.
In the mean time, the struct resolution linked to the server doesn't
need anymore to store the hostname in domain name format. A simple
pointer to the server one will make the trick.
The function srv_alloc_dns_resolution() properly manages everything for
us: memory allocation, pointer updates, etc...
3. move resolvers pointer into struct server
This patch makes the pointer to struct dns_resolvers from struct
dns_resolution obsolete.
Purpose is to make the resolution as "neutral" as possible and since the
requester is already linked to the resolvers, then we don't need this
information anymore in the resolution itself.
A couple of new functions to allocate and free memory for a DNS
resolution structure. Main purpose is to to make the code related to DNS
more consistent.
They allocate or free memory for the structure itself. Later, if needed,
they should also allocate / free the buffers, etc, used by this structure.
They don't set/unset any parameters, this is the role of the caller.
This patch also implement calls to these function eveywhere it is
required.
Some DNS related network sockets were closed without unregistering their file
descriptors from their underlying kqueue event sets. This patch replaces calls to
close() by fd_delete() calls to that to delete such events attached to DNS
network sockets from the kqueue before closing the sockets.
The bug was introduced by commit 26c6eb8 ("BUG/MAJOR: dns: restart sockets
after fork()") which was backported in 1.7 so this fix has to be backported
there as well.
Thanks to Jim Pingle who reported it and indicated the faulty commit, and
to Lukas Tribus for the trace showing the bad file descriptor.
AF_INET address family was always used to create sockets to connect
to name servers. This prevented any connection over IPv6 from working.
This fix must be backported to 1.7 and 1.6.
A "weakness" exist in the first implementation of the parsing of the DNS
responses: HAProxy always choses the first IP available matching family
preference, or as a failover, the first IP.
It should be good enough, since most DNS servers do round robin on the
records they send back to clients.
That said, some servers does not do proper round robin, or we may be
unlucky too and deliver the same IP to all the servers sharing the same
hostname.
Let's take the simple configuration below:
backend bk
srv s1 www:80 check resolvers R
srv s2 www:80 check resolvers R
The DNS server configured with 2 IPs for 'www'.
If you're unlucky, then HAProxy may apply the same IP to both servers.
Current patch improves this situation by weighting the decision
algorithm to ensure we'll prefer use first an IP found in the response
which is not already affected to any server.
The new algorithm does not guarantee that the chosen IP is healthy,
neither a fair distribution of IPs amongst the servers in the farm,
etc...
It only guarantees that if the DNS server returns many records for a
hostname and that this hostname is being resolved by multiple servers in
the same backend, then we'll use as many records as possible.
If a server fails, HAProxy won't pick up an other record from the
response.
The function dns_init_resolvers() is used to initialize socket used to
send DNS queries.
This patch gives the function the ability to close a socket before
re-opening it.
[wt: this needs to be backported to 1.7 for next fix]
The recent CLI reorganization managed to break these two commands
by having their parser return 1 (indicating an end of processing)
instead of 0 to indicate new calls to the io handler were needed.
Namely the faulty commits are :
69e9644 ("REORG: cli: move show stat resolvers to dns.c")
32af203 ("REORG: cli: move ssl CLI functions to ssl_sock.c")
The fix is trivial and there is no other loss of functionality. Thanks
to Dragan Dosen for reporting the issue and the faulty commits. The
backport is needed in 1.7.
dns_init_resolvers() tries to emit the current resolver's name in the
error message in case of out-of-memory condition. But it must not do
it when initializing the trash before even having such a resolver
otherwise the user is certain to get a dirty crash instead of the
error message. No backport is needed.
The analyse of CNAME resolution and request's domain name was performed
twice:
- when validating the response buffer
- when loading the right IP address from the response
Now DNS response are properly loaded into a DNS response structure, we
do the domain name validation when loading/validating the response in
the DNS strcucture and later processing of this task is now useless.
backport: no
New DNS response parser function which turn the DNS response from a
network buffer into a DNS structure, much easier for later analysis
by upper layer.
Memory is pre-allocated at start-up in a chunk dedicated to DNS
response store.
New error code to report a wrong number of queries in a DNS response.
In dns_send_query(), ret was set to 0 but always reassigned before the
usage so this initialisation was useless.
The send_error variable was created, assigned to 0 but never used. So
this variable is just useless by itself. Removing it.
Alexander Lebedev reported that the response bit is set on SPARC when
DNS queries are sent. This has been tracked to the endianess issue, so
this patch makes the code portable.
Signed-off-by: Nenad Merdanovic <nmerdan@anine.io>
Alexander Lebedev reported that the DNS parser crashes in 1.6 with a bus
error on Sparc when it receives a response. This is obviously caused by
some alignment issues. The issue can also be reproduced on ARMv5 when
setting /proc/cpu/alignment to 4 (which helps debugging).
Two places cause this crash in turn, the first one is when the IP address
from the packet is compared to the current one, and the second place is
when the address is assigned because an unaligned address is passed to
update_server_addr().
This patch modifies these places to properly use memcpy() and memcmp()
to manipulate the unaligned data.
Nenad Merdanovic found another set of places specific to 1.7 in functions
in_net_ipv4() and in_net_ipv6(), which are used to compare networks. 1.6
has the functions but does not use them. There we perform a temporary copy
to a local variable to fix the problem. The type of the function's argument
is wrong since it's not necessarily aligned, so we change it for a const
void * instead.
This fix must be backported to 1.6. Note that in 1.6 the code is slightly
different, there's no rec[] array, the pointer is used directly from the
buffer.
On some architectures, unaligned access is not authorized. On most
architectures, it is just slower. Therefore, we have to use memcpy()
when an unaligned access is needed, specifically when writing the qinfo.
Also remove the unaligned access when reading answer count when reading
the answer. It's likely that this instruction was optimized away by the
compiler since it is unneeded. Add a comment to explain why we use 7 as
an offset instead of 6. Not an unaligned offset since "resp" is
"unsigned char", then promoted to int.
060e57301d introduced a bug, related to a
dns option structure change and an improper rebase.
Thanks Lukas Tribus for reporting it.
backport: 1.7 and above
After Cedric Jeanneret reported an issue with HAProxy and DNS resolution
when multiple servers are in use, I saw that the implementation of DNS
query type update on resolution timeout was not implemented, even if it
is documented.
backport: 1.6 and above
A bug leading HAProxy to stop DNS resolution when multiple servers are
configured and one is in timeout, the request is not resent.
Current code fix this issue.
backport status: 1.6 and above
Instead of repeating the type of the LHS argument (sizeof(struct ...))
in calls to malloc/calloc, we directly use the pointer
name (sizeof(*...)). The following Coccinelle patch was used:
@@
type T;
T *x;
@@
x = malloc(
- sizeof(T)
+ sizeof(*x)
)
@@
type T;
T *x;
@@
x = calloc(1,
- sizeof(T)
+ sizeof(*x)
)
When the LHS is not just a variable name, no change is made. Moreover,
the following patch was used to ensure that "1" is consistently used as
a first argument of calloc, not the last one:
@@
@@
calloc(
+ 1,
...
- ,1
)
In C89, "void *" is automatically promoted to any pointer type. Casting
the result of malloc/calloc to the type of the LHS variable is therefore
unneeded.
Most of this patch was built using this Coccinelle patch:
@@
type T;
@@
- (T *)
(\(lua_touserdata\|malloc\|calloc\|SSL_get_app_data\|hlua_checkudata\|lua_newuserdata\)(...))
@@
type T;
T *x;
void *data;
@@
x =
- (T *)
data
@@
type T;
T *x;
T *data;
@@
x =
- (T *)
data
Unfortunately, either Coccinelle or I is too limited to detect situation
where a complex RHS expression is of type "void *" and therefore casting
is not needed. Those cases were manually examined and corrected.
This options prioritize th choice of an ip address matching a network. This is
useful with clouds to prefer a local ip. In some cases, a cloud high
avalailibility service can be announced with many ip addresses on many
differents datacenters. The latency between datacenter is not negligible, so
this patch permitsto prefers a local datacenter. If none address matchs the
configured network, another address is selected.
DNS selection preferences are actually declared inline in the
struct server. There are copied from the server struct to the
dns_resolution struct for each resolution.
Next patchs adds new preferences options, and it is not a good
way to copy all the configuration information before each dns
resolution.
This patch extract the configuration preference from the struct
server and declares a new dedicated struct. Only a pointer to this
new striuict will be copied before each dns resolution.
This function should return a 16-bit type as that is the type for
dns header id.
Also because it is doing an uint16 unpack big-endian operation.
Backport: can be backported to 1.6
Signed-off-by: Thiago Farina <tfarina@chromium.org>
Signed-off-by: Baptiste Assmann <bedis9@gmail.com>
A bug lied in the parsing of DNS CNAME response, leading HAProxy to
think the CNAME was improperly resolved in the response.
This should be backported into 1.6 branch
Basically, it's ill-defined and shouldn't really be used going forward.
We can't guarantee that resolvers will do the 'legwork' for us and
actually resolve CNAMES when we request the ANY query-type. Case in point
(obfuscated, clearly):
PRODUCTION! ahayworth@secret-hostname.com:~$
dig @10.11.12.53 ANY api.somestartup.io
; <<>> DiG 9.8.4-rpz2+rl005.12-P1 <<>> @10.11.12.53 ANY api.somestartup.io
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 62454
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 4, ADDITIONAL: 0
;; QUESTION SECTION:
;api.somestartup.io. IN ANY
;; ANSWER SECTION:
api.somestartup.io. 20 IN CNAME api-somestartup-production.ap-southeast-2.elb.amazonaws.com.
;; AUTHORITY SECTION:
somestartup.io. 166687 IN NS ns-1254.awsdns-28.org.
somestartup.io. 166687 IN NS ns-1884.awsdns-43.co.uk.
somestartup.io. 166687 IN NS ns-440.awsdns-55.com.
somestartup.io. 166687 IN NS ns-577.awsdns-08.net.
;; Query time: 1 msec
;; SERVER: 10.11.12.53#53(10.11.12.53)
;; WHEN: Mon Oct 19 22:02:29 2015
;; MSG SIZE rcvd: 242
HAProxy can't handle that response correctly.
Rather than try to build in support for resolving CNAMEs presented
without an A record in an answer section (which may be a valid
improvement further on), this change just skips ANY record types
altogether. A and AAAA are much more well-defined and predictable.
Notably, this commit preserves the implicit "Prefer IPV6 behavior."
Furthermore, ANY query type by default is a bad idea: (from Robin on
HAProxy's ML):
Using ANY queries for this kind of stuff is considered by most people
to be a bad practice since besides all the things you named it can
lead to incomplete responses. Basically a resolver is allowed to just
return whatever it has in cache when it receives an ANY query instead
of actually doing an ANY query at the authoritative nameserver. Thus
if it only received queries for an A record before you do an ANY query
you will not get an AAAA record even if it is actually available since
the resolver doesn't have it in its cache. Even worse if before it
only got MX queries, you won't get either A or AAAA
